Alkali and heat stability of polyols are important in a number of industrial and food applications. The confectionary, pharmaceutical and oral and dental hygiene industries and even chemical industries use polyol compositions, which are highly chemically stable in alkaline medium.
EP 0 711 743 describes the preparation of alkaline and heat stable polyol compositions wherein the stabilisation is either obtained through fermentation, oxidation or caramilisation.
EP 1 095 925 describes an alkali and heat stabilisation treatment. After this treatment the polyol is subjected to a purification step with at least one passage over a strongly acid cationic resin at a temperature below 30° C.
In JP 63079844, a method is described in which an aqueous sugar alcohol solution is adjusted to a pH-value of between 8 and 13, followed by a (discontinuous) heating step at temperatures varying between 90° C. and 220° C. The resulting product is then purified by passing the polyol solution through a strong acidic cation exchange resin, a strong anion exchange resin and a mixed bed resin.
WO 03/066553 describes a method for preparing alkali and heat stable polyols and the purification step involves a double passage over a cationic, anionic ion-exchanger configuration (CACA), comprising at least a first weak acid cationic ion exchanger resin and a second strong, medium or weak alkaline anionic ion-exchanger resin.
WO 2004/058671 describes a process for preparing alkali and heat-stable polyols by treatment with a strong anion exchange resin in the hydroxide form. In a multiple column-system at least part of the columns of the system are used in the regeneration mode, while the remaining columns are used in a service mode.
Currently there is a need for a simple, cost-effective process which allows obtaining alkali and heat stable polyols and the current invention provides such a process.